bpf_seccomp_filter.c

/*
 * Decoder of seccomp filter programs.
 *
 * Copyright (c) 2015-2017 Dmitry V. Levin <ldv@altlinux.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "defs.h"

#include "bpf_filter.h"

#include <linux/filter.h>
#ifdef HAVE_LINUX_SECCOMP_H
# include <linux/seccomp.h>
#endif
#ifndef SECCOMP_RET_ACTION_FULL
# define SECCOMP_RET_ACTION_FULL 0xffff0000U
#endif
#include "xlat/seccomp_ret_action.h"

static bool
print_seccomp_filter_k(const struct bpf_filter_block *const fp)
{
	if (BPF_CLASS(fp->code) == BPF_RET) {
		unsigned int action = SECCOMP_RET_ACTION_FULL & fp->k;
		unsigned int data = fp->k & ~action;

		printxval(seccomp_ret_action, action, "SECCOMP_RET_???");
		if (data)
			tprintf("|%#x", data);

		return true;
	}

	return false;
}

void
print_seccomp_fprog(struct tcb *const tcp, const kernel_ulong_t addr,
		    const unsigned short len)
{
	print_bpf_fprog(tcp, addr, len, print_seccomp_filter_k);
}

void
decode_seccomp_fprog(struct tcb *const tcp, const kernel_ulong_t addr)
{
	decode_bpf_fprog(tcp, addr, print_seccomp_filter_k);
}